Dr. Zakir Naik is one of the Greatest scholar of modern times. He preaching are soley based on Quran and Sahih hadeeth. The best thing is that he never tried to make sects in Islam and never abused other sects or even other religions.
But he's been hugely criticized in Pakistan and India because of calling Yazeed "Yazeed (RA)". In this he clarifies that why he called him so.